Knowledge and understanding of the uses, strengths,
limitations, and other characteristics of structural
metals is vital to properly construct and maintain any
equipment, especially airframes. In aircraft maintenance
and repair, even a slight deviation from design
specification, or the substitution of inferior materials,
may result in the loss of both lives and equipment. The
use of unsuitable materials can readily erase the finest
craftsmanship. The selection of the correct material for
a specific repair job demands familiarity with the most
common physical properties of various metals